A new method of feature line integration for construction of DEM in discontinuous topographic terrain

In cities and other areas of human activity, the implementation of various ground projects has resulted in significant changes to natural surface morphology, a prominent feature of which is the formation of a variety of discontinuous terrains, such as roads and building basements. These discontinuous terrains result in obvious topographic distortions of the digital elevation model (DEM) constructed by traditional modeling methods, which limits the applicability of DEMs to these areas. To solve these problems, this paper proposes a DEM modeling method to enhance the expression of discontinuous terrain from the perspective of simplicity and convenience of application. The method is based on terrain data such as topographic feature lines, altimetric points, and contour lines. First, parallel feature lines are generated according to a certain distance. Then, vertices are inserted onto the topographic feature line and the parallel feature line according to a specified step length, and known altimetric points are selected from both sides of the original topographic feature line to estimate the height values of the vertices. Finally, by combining the topographic feature line, parallel feature line and other available topographic data for TIN construction, the result can effectively express the special topography of discontinuous terrain. In this study, a region in Nanjing City, Jiangsu Province, China, was selected as the study area to conduct a DEM construction experiment. The experimental results showed that the DEM constructed using this method can well express the morphological characteristics of discontinuous terrain, and the height accuracy of the construction results was also significantly improved compared with that of a conventional method.